The present invention relates to an electromagnetic actuating device and to an armature unit.
A generic device is known in general from the prior art and is described for example in connection with DE 20 2005 012 297 by the Applicant, and especially in connection with FIGS. 6 and 7 therein. More specifically, in such generic devices, an armature unit is moved in a manner otherwise known per se by passing a current through a coil surrounding it in order to control a fluid flow by means of the movement of the armature unit. Typical uses include for example hydraulic or pneumatic valves, and these are in turn typically used in the vehicle industry.
FIG. 8 (cross-sectional view of a known armature unit) and FIG. 9 (perspective view of the armature unit shown in FIG. 8) illustrate such an armature unit which is presumed to be known. An armature body 10 made of a suitable magnetic material has in the circumferential region two elongate ventilation grooves 12 which serve for the described fluid flow. For sealing purposes and for weight reasons, the interior of the described armature unit is moreover filled with a respective vulcanized elastomer (14) which forms wide sealing regions 16 and 18 in respective end regions of the armature body 10. When this illustrated armature unit is used as intended within an electromagnetic actuating device, a fluid flow would then take place through the channels 12 in a manner suitably influenced by moving the armature unit.
However, such a device is disadvantageous for various reasons, in particular with regard to easy and automated manufacture (which is important from the mass production point of view). For example, in the device deemed to be generic, (fully) automated production of the complete armature is difficult to achieve since the illustrated technology requires smooth grinding. Furthermore, the manufacture of the illustrated arrangement with the known fluid guiding channels (ventilation grooves) 12 leads to the formation of burrs, which in turn mean that complex post-machining is required.
The illustrated grooves also have magnetic disadvantages (magnetic losses and thus potentially a reduction in the achievable magnetic force occur on account of the interruption or widening of the air gap in the circumferential direction that is brought about thereby). The illustrated groove contour is susceptible to wear during long-term use and (in a manner mechanically associated with this disadvantage) generates disadvantageous friction when moving in the stationary core unit.
Finally, the illustrated groove geometry which is presumed to be generic for forming the fluid flow channels gives rise to a disadvantageous tilting of the armature relative to the surrounding guide, so that there is also the potential for optimization here.
The object of the present invention is therefore to improve an electromagnetic actuating device according to the preamble of the main claim with regard to its manufacturing properties, magnetic and mechanical properties, in particular to optimize the potential for automated manufacture, to increase the achievable magnetic force, and in the process to reduce friction and wear on the armature.